Dead Orbit's entire spiel is that Earth is a dead end, so we should pack up, run far away, then aggressively expand until we're flung so far across the stars no single threat can ever hope to bring us this close to extinction again. Now, that doesn't sound bad on itself, but this is an impossible feat. Now, even if we assume we have the resources to even start seriously considering this plan (we don't), the lore, particularly the Book of Sorrow shows this is still impossible. The Darkness is simultaneously a conscious entity, a philosophy, and a fundamental force of existence. It's philosophy demands the extinction of all life. It can and has consumed entire civilizations far more expansive and advanced than Dead Orbit can even begin to dream of. You cannot outrun the Darkness, and there is no such thing as expansive enough so that it cannot consume us. Now, the Darkness is opposed by the Light, a philosophy which wants to nurture and encourage cooperation between all life. The Light is championed by the Traveler, and the Traveler is the only entity with even the most remote chance of dealing a meaningful enough defeat to the Darkness to stop it. Not only are our fates staked upon it, but the fate of all life in existence is. Without the Traveler and the Light we have no chance at survival, and Dead Orbit's plan involves abandoning Earth, meaning leaving a comatose Traveler defenseless, unable to heal, and right where the Darkness knows it is. So all of Dead Orbit is basically a trade off, we can continue doing what we're doing (under the Vanguard and FWC's philosophies) where we have a chance of being wiped out very soon, but a chance at winning and securing our survival, or we can go the Dead Orbit route where we guarantee the extinction of not only ourselves, but all life in the universe, but maybe buy ourselves a few centuries by just running continuously. In the alternate version of the Paradox mission you can even find a dead ghost that shows a possible future, one where Dead Orbit got what they wanted. We're painted a picture of a battered a broken fleet hounded across the stars by an unstoppable foe until our inevitable defeat. Not a very promising future.